I totally agree that a DAC can make an impact. But when a typical room response guarantee you a 30db null somewhere in the bass region (my room for example has a 30db null at 80hz, so that particular note completely disappeared at my listening position), I think room treatment is the single biggest improvement you can bring to your system after your speakers as you flatten your in room frequency response as well as reducing ringing which no amount of EQ can improve.

I have had a set of Altech Lansing A7 voice of the theater speakers that had a similar null that occurred between the port & the woofer at the same frquency ( about 80Hz ) but when used for thier designed purpose which is listening to music or watching movies thier sound was really second to none especially with my modded tube amp that I had at the time. The mods to that amp were suggested to me by a former electronics engineer that was the lead engineer at A & M studios back in the mid to late 1960's. I performed the actual mods myself to his specs.

These speakers with only 25 watts of pure class A tube power with zero feedback driving them could blow you out of the house with shear power but still have great finess at the same time. The woofer on that speaker was locked down pretty tight by its air load & rarely moved more than the thickness of its paper cone but generated bass power that could flutter you pant legs & cause the refridgerater upstairs to vibrate quite loudly due to bass coming through the floor it was sitting on. Bass on these speakers went no lower than 50 Hz but had lots of power down to that point. While many high-end speakers have textbook flat response few could generate the realism of those particular speakers driven with true class A vacuum tube electronics. Note that these speakers can sound really horrid though with solid state electronics driving them. They were designed around vacuum tubes which can have a matched output impedance. These speakers high efficiency will expose solid state foibles even if you form an impedance matching resistor network as that is the only way these speakers sound even remotely good with solid state. With the impedance matching network your 100 watt solid state amp becomes a 25 watt amp but even though the trade off is beneficial it is still not up to tube standards. This impedance matching resistor network was also suggested by the same electronics engineer that instructed me on the tube amp mods. They frequently used these speakers at A & M studios for mix down & monitoring especally on movie soundtrack as these were the most likely speakers to be used in the theaters but also for music as well